A Pluto ocean is deep under the dwarf planet's surface, astronomers think, and it could contain as much water as all the seas on Earth.

The discovery was published in the journal Nature on Wednesday, said the Huffington Post. and was made after NASA’s New Horizons spacecraft flew past Pluto back in July 2015, collecting images and data.

Scientists are focusing on a region of Pluto called Sputnik Planitia, according to Fox News. The region is “a big, elliptical hole in the ground, so the extra weight must be hiding somewhere beneath the surface. And an ocean is a natural way to get that,” said Francis Nimmo, one of the study’s authors and a professor at the University of California, Santa Cruz.

”Pluto is hard to fathom on so many different levels,” said Richard Binzel, a co-author and professor at MIT. “People had considered whether you could get a subsurface layer of water somewhere on Pluto. What’s surprising is that we would have any information from a flyby that would give a compelling argument as to why there might be a subsurface ocean there.”

Nimmo said Pluto’s ocean is “likely slushy with ice” and lies more than 90 miles beneath the planet’s icy surface, per the Huffington Post.

“We calculated Pluto’s size with its interior heat flow, and found that underneath Sputnik Planitia, at those temperatures and pressures, you could have a zone of water-ice that could be at least viscous,” Binzel said, per Fox News. “It’s not a liquid, flowing ocean, but maybe slushy.”

“It shows that nature is more creative than we are able to imagine, which is why we go and explore,” he said. “We see what nature is capable of doing.”

The new finding also raises the question of life on Pluto, considering that liquid water is one major ingredient of life.

“The evidence is looking pretty convincing that far from being a solid, frozen, boring ball of rock and ice, Pluto may have an internal ‘dark’ ocean, probably laced with stuff like ammonia,” said Caleb Scharf, the director of astrobiology at Columbia University.

“If we’re right, oceans in the outer solar system are common, and other objects of similar size to Pluto there probably also have subsurface oceans,” Nimmo said, per PBS.